What is acceleration?

What are the answers to these acceleration problems?

• I'm sorry I'm just in a hurry... 1. A car starts from rest and accelerates to a speed of 50 km/hr in 15 sec. What is its acceleration in km/sec^2? 2. A car is going 30 m/sec and has to stop for a dead pig in the road. What is its acceleration if it takes 25 seconds to stop? 3. How long will it take a car to go 50 meters if it starts at rest and accelerates at a rate of 15 m/sec^2? 4. A car is going 15 m/sec and increases its speed to 25 m/sec in 10 seconds. what is its acceleration?? THANKSS =D

• Answer:

  1- a = dv / dt = 50km / 15 = 3.333km/s2 2- a = dv / dt = 30 / 25 = -1.2 m/s 3- e = 1/2 a * t^2 t^2 = 2e / a = 50*2/ 15 = 6.6666 t = 2.582s 4- a = dv / dt = (25-15) /10 = 1m/s2 Goodbye